I worked in Malaysia for the Shah Alam Expressway Project. We used concrete spun piles; each pile section was 12 meter length. We even drove piles to 48 meters. The soil was there peat to a great depth. In fact piles even 24 meter pentrates with self weight. My advise is that drive the pile...
Four years age, I performed the geotechnical analysis for the similar project at Philadelphia Naval Business Center. The soft layer (CL, CH and MH) was 15 to 40 feet thick. The surcharge was 9 to 12 feet high. The area of surcharge was about 5700 x 100 to 140 ft.
We installed six piezometers...